No, constrained isn't conforming.  Poser dynamic cloth is kind of unique in that it has five different ways you can define parts of your cloth: dynamic, soft decorated, hard decorated, constrained, and choreographed.  Soft and hard decorations don't quite work like you might expect, but to put it simply they follow the dynamic mesh.  Constrained follows the colliding mesh (usually your figure) exactly. The effect is similar to conforming, but the actual behavior is very different.  Think of it more like dynamic cloth without the dynamics.  It follows poses and morphs, but doesn't wrinkle or respond to gravity.  Choreographed just stays wherever you put it, and won't change with the pose or morph.  If you want to make something that mainly works like a regular smart prop while having a dynamic part, choreographed parts are useful.  An earring with a dangly part, a mask with a veil, that sort of thing. 

Because constrained parts follow the figure mesh exactly, morphs can cause distortions.  Also, they'll follow the mesh exactly, not drape or stretch.  I've made shoes and boots that work great being constrained around the foot.  Thing is, most people don't morph feet much, so that's fine.   If you constrain an area on the lower half of a figure's breasts, and the figure goes from A to DDD with a big crease underneath and between the breasts, the constraned area will duplicate the change and crease in the same places.

That said, the most complex dynamic items I know of use constrained parts for things like the top of pants with belt loops, belts, and buckles.  I've tried to make that combo work  other ways, and it just plain didn't.  Cocco's dress pants just constrain the lot, and everything works together well.  But if I tried to use them on a character with a huge beer belly or a zombie that's almost flesh and bones, my guess is that belt would look awful, especially the buckle.  Considering there's not a huge number of people rendering those types of figures, it's not a huge issue. 

Esha's pareo over at RDNA that goes around the neck and overlaps itself much like that jacket uses constrained groups for the overlapping parts.  I haven't tested it, but it might not work so well on extreme breast morphs. 

That all said, dynamics won't necessarily solve your issue with shoulders.  I know how to address it in dynamic clothes and have done it, but it's also possible to do something similar with conformers.   Defined shoulders in jackets is standard feature of Uzilite's work, found at DAZ3D.  I'm guessing it's hard, because most people don't do it.  Conformers aren't really my thing, so I don't know much about making them.  But I've seen conforming clothes with good shoulders.

Dynamic clothing this complex wouldn't be something I'd recommend to a person who just wanted a jacket with proper shoulders.   Even for an average dynamic top with sleeves, you'd have to be careful about intersections at the shoulder and elbow.  With something as thick and stiff as a leather jacket, it would be even more of a concern.  As in real life, the jacket would somewhat restrain your figure's movements.  And that's before considering the how all those details would behave.  Depending on how you used it and your expectations, getting the performance you want out of it could be difficult or even impossible.  To be happy with it, you'd have to be happy with everything dynamic clothing does, not just happy with the shoulders.